The office is on the sixth floor, Riegsecker’s favorite number. And the building fits into the “Centro” theme — it's at the center of Chicago’s grid system. “It just felt like there was really great, almost cosmic, energy for us,” he said.

The office is on the sixth floor, Riegsecker’s favorite number. And the building fits into the “Centro” theme — it's at the center of Chicago’s grid system. “It just felt like there was really great, almost cosmic, energy for us,” he said.

Since its days based in a server room, Centro has had offices in River North. But when the company outgrew its space on West Hubbard Street, it decided it needed room to stretch. The company staked out a spot in Sullivan Center, the late-19th century building at State and Madison streets that used to house Carson, Pirie, Scott. The landmark building also is home to gift-card startup Raise and architecture firm Gensler. Founder and CEO Shawn Riegsecker showed us around.